1. Field of the Invention
The invention relates to a needle register for pickling machines, comprising one or more needles that are fed with brine from a pressurized chamber, and valves assigned to the individual needles, for controlling the flow of brine.
2. Description of the Related Art
One needle register of this type is known from DE 198 27 685 C2, in which the open, upper ends of the needles lead into the pressurized chamber; each needle thus forms a valve face for the valve needle assigned to it. The valve needles extend vertically into the pressurized chamber and out through its cover, such that a tight seal is formed but the valve needles can still be shifted. In this way, they can be manipulated from outside the pressurized chamber. The opening and closing of the valves is controlled via the relative movement between the needle register and a plate clamp, as is common in pickling machines. When the needle register and the needles are lowered, the plate clamp comes to rest against the item to be pickled, while the needles are inserted into it. With this known design, a high degree of functional reliability, ease of cleaning, and a low susceptibility to valve contamination are achieved.
The object of the invention is to simplify the design of the valves while retaining the high degree of functional reliability and to further decrease susceptibility to contamination.
This object is attained in accordance with the invention in that each needle is attached to the pressurized chamber via a piece of flexible tubing, and in that the valves are formed by squeezing-off mechanisms assigned to the pieces of flexible tubing.
In accordance with the invention, the closing of the valves is accomplished by squeezing off the pieces of flexible tubing. In contrast with traditional valve constructions, a precise fit between the valve needle and the valve face is not necessary, hence the high degree of functional reliability can be retained with a simplified construction and lower manufacturing costs. When squeezed off, the flexible material of the pieces of tubing ensures that the valves close completely, so that contamination and dimensional tolerances determined by manufacturing can be tolerated at a much higher level than with the traditional construction.
Furthermore, the pieces of flexible tubing allow greater constructive freedom in terms of the arrangement and design of the valve mechanics.
Advantageous embodiments of the invention are given in the sub-claims.
The flexible pieces of tubing are preferably comprised of a rubber-elastic material, such as silicon rubber, that will not be chemically altered by the pickling brine. Because of their inherent elasticity, the pieces of flexible tubing can also provide the restoring force for the squeezing-off mechanisms, thus allowing further design simplification.
The pieces of flexible tubing may be designed simply as short connecting pieces that are placed on the upper ends of the pickling needles, which lead into the pressurized chamber.
The squeezing-off mechanism is preferably formed by a compression element that can be moved laterally in relation to the piece of flexible tubing, and by an abutment that is attached firmly in relation to the needles to the side of the piece of flexible tubing that is opposite the compression element. Further, the lower section of the abutment may be designed as a bushing, in which the upper end of the needle and the piece of flexible tubing that is placed on the needle are fastened.
In principle, each needle may be equipped with a separate operating mechanism, so that the needles are individually controllable. In one preferred embodiment, however, the needles are combined into one or more groups, whose compression elements are controlled by a common operating mechanism. In this case, the operating mechanism can be designed as a tappet that extends, leakproof, through the wall of the pressurized chamber. The advantage of this design is that for each group of needles only a single pressure-tight lead-in for the tappet need be provided in the pressurized chamber. The compression elements for all the needles in the group can then be formed by a latticed gate, the lattice openings of which conform to the placement of the needles. If the pressurized chamber has a removable cover, the gate can simply be placed in the pressurized chamber after the cover has been removed.
With needle registers that have a relatively large working area it may occur that in pickling smaller items only some of the needles are needed. In this case, it is possible to replace the gate, which is operated via the tappet, with a smaller gate, and to close off the unused needles via a separate gate that is mounted in the pressurized chamber such that it cannot move.
For operating the tappet, all known operating mechanisms present possible options, including cam or lever controls, or even pneumatic, hydraulic, or electric controls.